As a general rule, the electronic memory cards used for performing electronic transactions, e.g. of the credit/debit type, have EEPROM or flash EPROM memories giving the two advantages of being non-volatile and of being electrically erasable, and thus of being rewritable. However they can be reprogrammed a limited number of times only and they take a long time to be programmed.
In certain applications, it can happen that these memories are corrupted for one or other of the following reasons:
too large a number of rewrite operations, wearing out certain memory cells and giving rise to faulty operation of the electronic memory; PA1 programming performed for a very short time only, giving rise to insufficient charge in the memory cells; and/or PA1 accidental interruption of the electrical power supply during programming, giving rise to the same effect, or indeed to earlier values being erased without new values being programmed.
This third risk is particularly important in applications such as electronic memory cards where said memory is on board an object whose power supply is external and from which it can be separated at all times.
Nevertheless, it can be seen that these causes of corruption giving rise to integrity defects in the data written in the rewritable memory are not equivalent. A memory that is misfunctioning because of cell wear is final and irreversible, whereas writing errors due particularly to the card being taken out of the terminal too soon or to the electronic component losing its power supply voltage are isolated accidents that do not involve the general operation of the system.